This invention is related to weight resistance exercise apparatus. More particularly, it is directed to improvements to an exercise apparatus having reciprocating weights.
The present invention improves the type of exercise apparatus disclosed by the inventor in U.S. Pat. Nos. 5,334,118 and 5,474,511. Those patents disclose exercise apparatus comprising a rigid rod with a sliding weight the movement of which is restrained along the length of the rod by coil springs at an end of the weight. The disclosed exercise apparatus embodiments have either a sliding handle or a stationary handle at the opposite end of each spring from the weight. Different muscle groups are exercised depending on how the apparatus is held and whether the handles are stationary or slidable.
The invention disclosed in those patents has some limitations. Exercises that call for one end of the apparatus being held against a vertical or horizontal surface while force is applied to a sliding handle are difficult to perform because the apparatus becomes unstable. Exercises that can be performed only with embodiments with sliding handles cannot be performed with embodiments with stationary handles, and visa versa. Also the difficulty in overcoming the resistance of the springs depends on the strength of the springs and the mass of the weight. A combination that is suitable for a strong person would be too difficult for a person with lessor strength. Conversely, a combination that is suitable for a person with lesser strength would be too easy for a strong person. These patents did not allow for changing the weights without a disassembly of the apparatus.